Coating could protect helicopter blades

The fine sand found in parts of Afghanistan and Iraq erodes and damages the blades of Apache, Chinook, and Blackhawk helicopters used by the military. So far, the repair and replacement of blades has cost the military almost a half-billion dollars. (New blades cost about $500,000/helicopter.) After evaluating over 150 different protective coatings, engineers at the Army Research Laboratory have come up with a two-coating approach that seems to stave off sand-caused damage. The first coating, tungsten carbide-cobalt (WC-Co), is applied to the blade’s leading edge using high-velocity air-fuel powder spraying. The second coating, cold-sprayed niobium, is put on the rest of the blade. If testing is successful, the coating will likely be common on Army helicopters deployed to desert regions.